U.S. Secretary of State John Kerry visited Iraq on Friday to show support for its prime minister who is grappling with a political crisis, a collapsing economy and a fight to retake ground from Islamic State militants.

According to Reuters, Prime Minister Haider al-Abadi last week unsettled Iraq's political elite with a proposed cabinet reshuffle that aims to curb entrenched corruption by replacing long-time politicians with technocrats and academics.

His aim is to free Iraqi ministries from the grip of a political class that has used the system of ethnic and sectarian quotas instituted after the U.S.-led invasion in 2003 to amass wealth and influence.

U.S. officials fear the political unrest may harm Iraq's efforts to retake territory it has lost to ISIl militants, notably its second city of Mosul, seized when parts of the Iraqi army collapsed in 2014.

"This is obviously a very critical time here in Iraq," Kerry said as he began a meeting with Foreign Minister Ibrahim al-Jaafari at his villa in Baghdad's heavily protected Green Zone which houses embassies and government buildings.

He later met with Abadi, who ignored a U.S. reporter's shouted question about whether he wanted Washington to deploy more troops to Iraq. The United States, which withdrew its forces from Iraq in 2011, has redeployed several thousand troops as part of a coalition it is leading against Islamic State.

Announcing Kerry's visit, U.S. State Department spokesman John Kirby said the trip "will underscore our strong support for the Iraqi government as it addresses significant security, economic and political challenges."

However, an offensive billed as the first phase of a campaign to recapture the northern city of Mosul has been put on hold until reinforcements arrive to hold ground, the commander of the operation said on Wednesday.

"The political wrangling in Iraq - it's certainly an issue that concerns us," a senior U.S. official in Washington told reporters earlier this week before Kerry flew to Iraq aboard a U.S. military aircraft.

Kerry plans to "encourage the Iraqis, while they're dealing with the cabinet reshuffle, not to lose sight of the need to stay focused on the fight against" Islamic State, he said, stressing the need "to plan steadily and carefully" to retake Mosul.

Baghdad is also hamstrung by the plunge in global oil prices that has shriveled its main source of revenue.

On Thursday, officials from the International Monetary Fund and the government said the oil price forecast in the 2016 budget would be cut to about $32 a barrel from $45, widening Iraq's fiscal deficit by several billion dollars.

Kerry also plans talks with the head of the Kurdistan Regional Government, Nechirvan Barzani, the State Department said.